Preparation of aqueous dispersions of synthetic rubbers



Patented Oct. 5, 1948 PREPARATION OF AQUEOUS DISPERSIONS OF SYNTHETICRUBBERS Charles F. Brown, Bethany, W. Va), assignor to United StatesRubber Company, New York, N. Y., a corporation of New Jersey No Drawing.Application January 29, 1947, Serial No. 725,171

20 Claims. 1

This invention relates to a method of preparing aqueous dispersions ofcertain synthetic rubbers, more particularly aqueous dispersions ofcertain synthetic rubbers on soaps as the dispersing agents.

Natural rubber, as is known, may readily be dispersed in water bymilling or otherwise plasticizing the rubber, incorporating ahydrophilic colloidal dispersing agent, for example soap,

'solubilized casein, or colloidal clay, and adding water whilestretching and kneading the plasticized mass, as in an internal mixer,such as a Werner & Pfleiderer type mixer, until an inversion of phasetakes place, and the rubber becomes dispersed in the aqueous medium.Gums, bitumens, and cellulose esters have been similarly dispersed inwater. Many synthetic resins, even after the addition of conventionalplasticizing agents, cannot be dispersed in water with soap as thedispersing agent because such synthetic resins are resistant to and willnot absorb soap-forming acids or soaps in such a manner that theaddition of Water thereto, as in an internal mixer, will cause aninversion ofphase and dispersion of the synthetic resin in the aqueousmedium. In these cases, the synthetic resin containing the soap breaksup in small pieces on addition of the water and the soap merely exudesto the surface of the pieces of synthetic resin.

By the present invention, aqueous dispersions of certain syntheticrubbers may readily be prepared with soaps as the dispersing agents.

In carrying out my invention, the heat-reaction product of rosin, analkanolamine, analkylene glycol, and a dimerized acid of a vegetabledrying oil is mixed with the synthetic resin befor dispersing the resinon the soap. This reaction product acts to improve the receptiveness ofthe synthetic resin to soap, whereby after the soap is milled in, Watermay be added as in an internal mixer until inversion of phase readilytakes place and the synthetic resin'becomes dispersed, together with theadded heat-reaction product, in the aqueous medium containing the soap.The heat-reaction product of rosin, an

alkanolamine, an alkylene glycol, and a dimerized acid of a vegetabledrying oil, and the method of preparing the same, is disclosed in mycopending application Serial No. 507, fi d to er 1943, now Patent No.2,416,433, granted February 25, 1947. As disclosed in that case, theglycol and dimerized acid of a vegetable drying oil may first be reactedto form a so-called polyester which itself is a known commercialsynthetic resin, sold under the trade names Norepol and Agripol. Thepolyester, or the glycol and dimerized acid of a vegetable drying oil,is reactedat elevated temperatures with rosin and an alkanolamine toform the heat-reaction product which is used in the present invention toaid in dispersing certain difficultly dispersible synthetic resins inwater. Examples of. the preparation of the heat-reaction product,according to my prior patent application Serial No. 507,295, are givenbelow.

The heat-reaction product may be produced by heating for about 5 to 15hours at a temperature from aboutl80 C. to 300 C., a mix containingrosin, an alkanolamine, an alkylene glycol and a dimerized acid of avegetable drying oil, or an equivalent mix containing rosin, analkanolamine and a polyester. The alkanolamine may be a mono or diortri-substituted alkanolamine, or a mixture thereof, e. g.,monoethanolamin'e, diethanolamine, tri-ethanolamine, although thetrisubstituted alkanolamines are preferred. The term polyester refers tothe synthetic resin obtained by reacting a glycol with a dimerized acidof a vegetable drying oil, such as soy bean oil, tung oil, linseed oil,or other unsaturatedvegetable oil acid. By dimerized is meant thecombination of two molecules of the unsaturated acid by additionpolymerization. These are the conventional meanings of the terms.

The reactions taking place between. the components present are variedand complex. The polyester when added as such probably breaks down intoits several reacting groups, which groups or bodies react with otherbodies present to give various products diflering from the orig inalreactants. The dimerized acid and glycol, when added separately, eitherprovide such reactive groups, or may react to give a polyester, whichinturn may give up reactive bodies as postulated. The dimerized acid andglycol, when added separately, should be added to a weight equivalent tothe weight of the polyester. For example, 87.5 parts of dimerized acidsof soy bean oil,;and 12.5 parts .of ethylene glycol, are equivalent toparts of the corresponding polyester. In some cases, an excess of theglycol may be used Parts Rosin -100 Triethanolamine 25-100 Polyester50-200 Preferred proportions, by weight, as illustrated by the examplesbelow, comprise about equal parts of the rosin (or its equivalent ofabietic acid) and the ethanolamine, together with from about 85 to about100 parts of the polyester based on each 100 parts of the rosin.

The following examples I to IV, in which the parts are by weight, aregiven in illustration of the invention:

Example I Parts Rosin 100 Triethanolamine 100 Polyester -i 100The-polyester and that of Example IIiis a combination prepared from adimerized acidderived from such as soy bean oil, said dimerized acidbe,- ing reacted with ethylene glycol and the reaction productcontaining about 12 /2% ethylene glycol. Itis sold under the trade nameNorepol.

The. rosin and the amine are mixed and heated to about 180 C. until the.ingredients 'form a homogeneous solution- Then the polyester is added.and thereaction mixtureisheated together ina suitable container at200-230 C. for about 9 or 1.0. hours, or until incipient gelling takesplace. At-the indication of. gelling, the mixture is dumped. from thereaction vessel and allowed to cool. The product is. a-dark, verysticky, adhesive, gel like resin that is insoluble in all of the commonsolvents, except the benzenoid and chlorinated hydrocarbons.

Example II The reaction product may be further modified by theincorporation of other resins. These resins serve to. add strength tothecomposition andto not-materially change the properties of the basicheat-reaction product. A preferred mixture is:

. Parts Rosin 100 Triethanolamine 100 Polyester 85 Poyvinyl butyra1resin 15 The reactionmixture is heated as in Example I. The product hascharacteristics substantially identical with that cited in Example Iexcept that the composition is stiffer and stronger.

Example III Itis not always necessary that the polyester be addedassuch. The ingredients may be added separately. The followingexample isillustrative:

The dimerized acid and that of Example IV corresponds to the dimerizedunsaturated long chain fatty acid or acids such as those derived fromsoy bean oil. The reactants. are heated together as in Example I and theheat-reaction product has characteristics equivalent to that of ExampleI.

Example IV A heat-reaction product corresponding to that produced inExample II is obtained from:

Parts Rosin 100 Triethanolamine 100 Dimerized a i 74.4 Ethylene: glycol10.6 Polyvinyl butyral resin 15 The reactants are heated together as inExample II, and the products obtained are substantially identical incharacteristics with those from Example II.

Products such as the above and illustrated in previous Examples I to IV,will be termed heatreaction products of rosin, an alkanol amine, aglycol-and'dimerized acid of a vegetable drying oil, or a'dimerizedunsaturated acid of a vegetable oil. Such resinousheat-reaction products may readily be milled into synthetic resins. Withcertain synthetic resins, the heat-reaction product will permit theadmixture of soaps with the synthetic resin mass and give an inversionof phase on-addition of water with dispersing of the syntheticresin andadded heat-reaction product in the aqueousmedium. The amount of theheatreaction product added to the synthetic resin is not-critical,additions of from 5 to 50 parts of the heat-reaction product of theabove examples per 10 parts of synthetic resin efiectively aiding thedispersing of the synthetic resin in water. In general,increased-amounts of the heat-reaction product give increasedviscosities, and increased tackto films laid down from the dispersions.

Synthetic rubbers which have been dispersed in water on soap as thedispersing agent with the aid of the above heat-reaction products arepolymers of b.utadienes-l,3, and copolymers of butadienes-1,3 with otherpolymerizable compounds. Illustrative of polymers of butadienes-1,3 arethe polymers of butadiene-l,3, methyl-2-butadiene- 1,3 (isoprene),chloro-2-butadiene-1,3 (chloroprene) piperylene(methyl-l-butadiene-lfi') and 2,3-dimethyl-butadiene-1,3. Illustrativeof the copolymers of butadienes-1,3with other polymer izable compoundswhich are capable of forming copolymers with butadienes-l,3, arecopolymers of the above illustrated butadienes-l,3 with up to 70% byweight Ofthe copolymer of compounds which contain a CHz=C group where atleast one of the disconnected valences is attached to an electroactivegroup, that is, a group which substantially increases the electricaldissymmetry of polar character of the molecule. Examples of suchcompounds which contain a CH2=C group and are copolymerizable withbutadienes-1,3 are aryl olefins, such as'styrene and vinyl naphthalene,the alpha-methylene carboxylic acids, and their esters, nitriles andamides, such as acrylic acid, methyl acrylate, methyl methacrylate,acrylonitrile, methacrylonitrile, methacrylamide, isobutylene, methylvinyl ether, methyl vinyl ketone, vinylidene chloride. Examples ofcommer- Y cial synthetic rubbers which are polymers or gosyntheticresins according to the present inven-- tion which may utilize theheat-reaction products of prior Examples I to IV as dispersing aids forthe synthetic resins prior to dispersing on soap. The soap may be addedas such or formed in situ in the synthetic resin mass. The soap may be aconventional soap dispersing agent, such as an alkali-metal, ammonium,alkylamine, alkanolamine, or morpholine soap. All parts in the followingexamples are by weight.

Example V 100 parts of commercial neoprene (polymerizedchloro-2-butadiene-1,3) were. mixed on a mill with parts of theheat-reaction product of Example I. To thethus plasticized neoprene wasadded 1 part of oleic acid and 1 part of water, whereupon the batch wastransferred to a Werner 8; Pfleiderer mixer and 4 more parts of oleicacid added. 1.25 parts of potassium hydroxide dissolved in a smallamount of water were added to neutralize the oleic acid and form thepotassium soap in situ. Water was then added slowly and inversion ofphase took place after the total addition of about 25 parts of water,whereupon the neoprene became dispersed in the water. Further water wasadded to the desired concentration of 60% solids.

Compounding and modifying ingredients, such as other resins, fillers,curatives, pigments, loading materials and the like, may be added to theplasticized mix on the mill or in the Werner & Pfleiderer mixer prior toaddition of water to inversion of phase, as in the case of dispersionsof natural rubber.

Example VI 100 parts of commercial Buna S rubber (copolymer of 75 partsby weight of butadiene with 25 parts by weight of styrene) were mixed ona mill with 15 parts of the heat-reaction product of Example II. Thisbatch was placed in a Werner & Pfleiderer mixer and 8 parts of stearicacid were added together with a small amount of water followed by 2parts of potassium hydroxide dissolved in a small amount of water toform the soap. Water was then added to inversion of phase.

Example VII 100 parts of commercial Buna N (copolymer of 75 parts byweight of butadiene with 25 parts by weight of acrylonitrile) were mixedon a mill with 25 parts of the heat-reaction product of Example IV. 6parts of oleic acid and a small amount of water were added, after whichthe mass was transferred to a Werner & Pfleiderer mixer where 1.3 partsof sodium hydroxide dissolved in a small amount of water were mixed in.Water was then slowly added with continuous kneading and stretching ofthe mass in the mixer until an inversion of phase took place and theBuna N rubber became dispersed in the aqueous medium. Examples V to VIIdisclose the dispersion of various synthetic resins according to thepresent invention using soap as the dispersing agent, soap dispersionsbeing the most difficult dispersions of synthetic resins to prepare dueto the resistance of the synthetic resins to the softening effects ofsoap-forming acids and soaps. However, the heat reaction products suchasshown in Examples I afforded the invention.

This application is a continuation-in-part of my application Serial No.559,651, filed October 20, 1944, now Patent No. 2,419,316, granted April29, 1947'.

Having thus described my invention, what I claim and desire to protectbyLetters Patent is:

1. The method of preparing an aqueous dispersion of synthetic rubberselected from the group consisting of polymers of butadienes-1,3selected from the group consisting of butadiene- 1,3,methy1-2-butadiene-1,3, chloro-2-butadiene 1,3, piperylene, and2,3-dimethyl-butadiene-1,3, and copolymers of such butadienes-1,3 withup to 70% by weight of the copolymer of compounds which contain a singleCH2=C group and are copolymerizable therewith, which comprises mixingwith such synthetic rubber a heat-reaction product, at a temperature inthe range of between about C. and 300 C., of a mix containing rosin, analkanolamine, an alkylene glycol and a dimerized acid of a vegetabledrying oil, and also a hydrophilic colloidal dispersing agent selectedfrom the group consisting of soaps, proteins, solubilized casein andcolloidal clay, and adding water until an inversion of phase takesplace.

2. The method of preparing an aqueous dispersion of synthetic rubberselected from the group consisting of polymers of butadienes-l,3selected from the group consisting of butadiene- 1,8,methyl-2-butadiene-1,3, chloro-Z-butadiene- 1,3. piperylene, and2,3-dimethyl-butadiene-1,3, and copolymers of such butadienes-1,3 withup to 70% by weight of the copolymer of compounds which contain a singleCH2==C group and are copolymerizable therewith, which comprises mixingwith such synthetic rubber a heat-reaction product,-at atemperature inthe range ofbetween about 180C. and 300 0., of a mix containing rosin,an alkanolamine, ethylene glycol and a dimerized acid of a vegetabledrying oil, and also a soap, and adding water until an inversion ofphase takes place.

3. The method of preparing an aqueous dispersion of synthetic rubberselected from the group consisting of polymers of butadienes-l .3selected from the group consisting of butadiene- 1,3,methyl-2-butadiene-1,3, chloro-2-butadiene- 1,3, piperylene, and2,3-dimethyl-butadiene-1.3. and copolymers of such butadienes-1,3 withup to 70% by weight of the copolymer of compounds which contain a singleCH2=C group and are copolymerizable therewith, which comprises mixingwith such synthetic rubber a heat-reaction product, at a temperature inthe range of between group consisting of polymers of. butadienes-l,3selected from the group consisting of butadiene- 1,3,methyl-2-butadiene-1.,3, chloro-Z-butadiene- 1,3, piperylene, and2,3-dimethyl-butadienel,3, and copolymers of, such butadienes-i,3withcup to 70% by weight of the copolymer of compounds which contain asingle CH2=C group and are copolymerizable therewith, which comprisesmixing with such synthetic rubber a heat-reaction product, at atemperature in the range of between about 180 C. and 300 C., ofa mixcontaining rosin, an alkanolamine, an alkylene glycol and dimerized acidof soy bean oil, and also mixing with the synthetic rubber a soap, andadding water until an inversion of phase takespl'ace.

5. The method of preparing-an aqueous dispersion of a syntheticrubbercopolymer ofbutacliche-1,3 with up to 70% by weight of the copolymer of styrene which comprises mixing with said synthetic rubberaheat-reaction product, at a temperature in the range of between about180 C. and 300 0., of a mix containing rosin, an alkanolamine, ethyleneglycol and a dimerized acid of a vegetable drying oil, and also mixingwith the synthetic rubber a hydrophilic colloidal dispersing agentselected from the group consisting of soaps, proteins, solubilizedcasein and colloidal clay, and adding water until an inversion of phasetakes place.

5. The method of preparing an aqueous dispersion of a synthetic rubbercopolymer of butadiene-l,3 with up to 70% by weight of the copolymer ofstyrene which comprises mixing with said synthetic rubber aheat-reaction product, at a temperature in the range of between about180 C. and 300 (3., of a mix containing rosin, an alkanolamine, analkylene glycol and dimerized acid of soy bean oil, and also mixing withthe synthetic rubber a soap, and adding water until an inversion ofphase takes place.

7. The method of preparing an aqueous dispersion of polymerizedchloro-2butadiene-1,3

which comprises mixing with said polymerized chioro-2-butadiene-1,3 aheat-reaction product, at a temperature in the range of between about180 C. and 300 C1, of a mix containing rosin, an alkanolamine, ethyleneglycol and a dimerized acid of a vegetable drying oil, and alsomixingwith the polymerized chloro-2-butadienel,3 a hydrophilic colloidaldispersing agent selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay, and adding water until aninversion of phase takes place.

8. The method of preparing an aqueous dispersion of polymerizedchloro2-butadiene-l,3 which comprises miXing with said polymerizedchloro-2-butadiene-1,3 a heat-reaction product, at a temperature in therange of between about 180 C. and 300 C., of a mix containing rosin, analkanolamine, an alkylene glycol and dimerized acid of soy bean oil, andalso mixing with the polymerized ch1oro-2-butadiene-l,3 a soap, andadding water until an inversion of phase takes place.

9. The method of preparing an aqueous dispersion of a synthetic rubbercopolymer of butacliche-1,3, at a temperature in the range of betweenabout 180 C. and 300 C., of a mix containing acrylonitrile whichcomprises mixing with said synthetic rubber a heat-reaction product, ata temperature in the range of between about 180 C. and 300? C.,'of a mixcontaining rosin, an alkanolamine, ethylene glycol and a dimerized acidof a vegetable drying oil, andxalso mixing with the synthetic rubber ahydrophilic colloidal polymer of acrylonitrile which comprises mixingwith said synthetic rubber a heat-reaction prodnot, at atemperatureinthe range of between about. 180? C. and 300 C., of a mix containingrosin, an alkanolamine, an alkylene glycol and dime-rized' acid of soybean-oil, andalso mixing with the synthetic rubber a soap, and addingwater until an inversion of phase takes place.

11. A composition of matter containing dispersed particles of a mixtureof synthetic rubber selected from the group consisting of polymers ofbutadienes-lfi selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay, and copolymers of suchbutadienes-1,3 with up to 70% by weight of the copolymer of compoundswhich contain a single CHz==C group and are copolymerizable therewith,with a heatreaction product, at a temperature in the range of betweenabout 180 C. and 300 C., of a mix containing rosin, an alkanolamine. analkylene glycol and a dimerized acid of a vegetable drying oil, in anaqueous medium containing a hydrophilic colloidal dispersing agentselected from the group consisting of soaps, proteins, solubilizedcasein and colloidal clay.

12. A composition of matter containing dispersed particles of a mixtureof synthetic rubber selected from the group consisting of polymers or"butadienes-1,3 selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay, and copolymers of suchbutadienes-l,3 with up to 70% by weight of the copolymer of compoundswhich contain a single CHz=C group and are copolymerizable therewith,with a heatreaction product, at a temperature in the range of betweenabout 180 C. and 300 C.. of a mix containing rosin, an alkanolamine,ethylene glycol and a dimerized acid of a'vegetable drying oil, in anaqueous medium containing soap.

13. A composition of matter containing dispersed particles of a mixtureof synthetic rubber selectedfrom the group consisting of polymers ofbuta'dienes-1,3 selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay, and copolymers of suchbutadienes-1,3 with up to 70% by weight of the copolymer of compoundswhich contain a single CH2=C group and are copolymerizable therewith,with a heatreaction product, at a temperature in the range of betweenabout 180 C. and 300 0., of a mix containing rosin, an alkanolamine,ethylene glycol and dimerized acid of soy bean oil, in an aqueous mediumcontaining a hydrophilic colloidal dispersing agent selected from thegroup consisting of soaps, proteins, solubilized casein and colloidalclay.

14. A composition of matter containing dispersed particles of a mixtureof synthetic rubber selected from the group consisting of polymers ofbutadienes-1,3 selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay, and copolymers of suchbutadienes-l,3 with up to 70% by weight of the copolymer of compoundswhich contain a single CH2=C group and are copolymerizable therewith,with a heatreaction product, at a temperature in the range of betweenabout 180 C. and 300 0., of a mix containing rosin, an alkanolamine, analkylene glycol and dimerized acid of soy bean oil, in an aqueous mediumcontaining soap.

15. A composition of matter containing dispersed particles of a mixtureof a synthetic rubber copolymer of butadiene-LB with up to 70% by weightof the copolymer of styrene with a heatreaction product, at atemperature in the range of between about 180 C. and 300 C., of a mixcontaining rosin, an alkanolamine, an alkylene glycol and dimerized acidof soy bean oil, in an aqueous medium containing a hydrophilic colloidaldispersing agent selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay.

16. A composition of matter containing dispersed particles of a mixtureof a synthetic rubber copolymer of butadiene-1,3 with up to 70% byweight of the copolymer of styrene with a heatreaction product, at atemperature in the range of between about 180 C. and 300 0., of a mixcontaining rosin, an alkanolamine, ethylene glycol and a dimerized acidof a vegetable drying oil, in an aqueous medium containing soap.

17. A composition of matter containing dispersed particles of a mixtureof polymerized chloro-2-butadiene-l,3 with a heat-reaction product, at atemperature in the range of between about 180 C. and 300 C., of a mixcontaining rosin, an alkanolamine, an alkylene glycol and dimerized acidof soy bean oil, in an aqueous medium containing a. hydrophiliccolloidal dispersing agent selected from the group consisting of soaps,proteins, solubilized casein and colloidal clay.

18. A composition of matter containing dispersed particles of a mixtureof polymerized chloro-2-butadiene-1,3 with a heat-reaction prodnot, at atemperature in the range of between about 180 C. and 300 0., of a mixcontaining rosin, an alkanolamine, ethylene glycol and a dimerized acidof a vegetable drying oil, in an aqueous medium containing soap.

19. A composition of matter containing dispersed particles of a mixtureof a synthetic rubber copolymer of butadiene-1,3 with up to by weight ofthe copolymer of acrylonitrile with a heat-reaction product, at atemperature in the range of between about C. and 300 C., of a mixcontaining rosin, an alkanolamine, an alkylene glycol and dimerized acidof soy bean oil, in an aqueous medium containing a hydrophilic colloidaldispersing agent selected from the group consisting of soaps, proteins,solubilized casein and colloidal clay.

20. A composition of matter containing dispersed particles of a mixtureof a synthetic rubber oopolymer of butadiene-1,3 with up to 70% byweight of the copolymer of acrylonitrile with a heat-reaction product,at a temperature in the range of between about 180 C. and 300 C., of amix containing rosin, an alkanolamine, ethylene glycol and a dimerizedacid of a vegetable drying oil, in an aqueous medium containing soap.

CHARLES F. BROWN.

No references cited.

